Pianoforte-action



UNITED sTATEs PATENT oEEToE.

WILLIAM MUNRoE, 0E BOSTON, MASSACHUSETTS.

PIANOFORTE-ACTION.

speciacation of Letters Patent N6. 12,763, datedApril 2a, 1855.

To all whom t may concern.'

Be itl known that I, VILLIAM MUNROE, of the city of Boston, county of Suffolk, and State of Massachusetts, have invented certain new and useful Improvements in the Action of Pianofortes and Reed-Organs; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, making part of this specification, in which- Figures 1, and 2, are side elevations of my improved action in different positions and in which similar letters refer to similar parts. l

It is a desideratum to produce an action that shall be at once cheap and simple in its construction, powerful in its operation, easy of adjustment, and not liable to derangement.

To accomplish this is the object of my invention, and to enable others skilled in the art to make and use it, I will proceed to describe its construction and operation.

The key hinged on its fulcrum (B) and cushioned in the usual manner bears the piece (C) to which the jack or hopper (D) is attached, its position being regulated by the adjusting screws (az) and (b). The end of the jack is notched and clothed similarly to the hammer butts of other actions so as to receive the continuation of the link (E) of the toggle joint which bears upon the notch of the jack when the action is at rest. Connected with the jack by wires, screw threaded for the purpose of adjustment, is the inclined escapement (F) and the check (G).

The toggle joint composed of the links (E) and (H) hinged together at (c) has its fixed fulcrum at the piece (I) which is screwed upon the rail (J), the movable ful-` crum being att-ached to the hammer butt (K). The hammer is hinged by its butt to the piece (L) which is fixed to the hammer rail (M), when the action is at rest the hammer bears upon the cushion (N). The strings or reeds of the instrument are represented by (O) against which the hammer strikes.

The damper and other appendages are not represented as they form no part of my invention. When the finger end of the key is depressed the jack rises and acts on the end of -the link (E) which bears on the notch of the jack; this movement straightens the toggle j o-int and throws forward the end of the link attached to the hammer butt, thus throwing the ,hammer against the String. During the upward motion of the jack the inclined escapement comes in contact with the hammer rail and is pushed therefrom carrying with it the jack and check. The hammer in rising acquires a momentum and is projected y beyond the positive action of the jack so as to strike the string; the reaction of the stringcauses the hammer to fly back where it is caught by the check acting on the hammer butt. which prevents theA hammer from rebounding against the string. When the finger end of the key is allowed to rise through a small portion of its movement the ack will descend proportionally and the weighted check will cause the end of the jack to move forward and engage the end of the link while the -hammer is held up by the top of the check in a position ready tov repeat the blow. In repeating the finger does not allow the key to rise to the full amount of its stroke consequently t-he hammer does not descend and bear on the cushion (N) but follows and rests on the top of the check (Gr) while the surface is disengaged from contact with the hammer butt, and the jack is drawn by the weighted check partially under the link (E) and obtains sufiicient engagement therewith to give the repeating blow, without it being necessary for the key to traverse through the whole of its movement. The uniformity of the resistance of the inclined escapement avoids the inequality of the touch occasioned by the abrupt resistance of the ordinary escapement.

To cause the finger end of the key to rise quickly from any depression thereof it is usual to weight its opposite end; by weighting the check I effect the same purpose as well as that of depressing it and thereby drawing the jack into contact with the link (E) of the toggle joint. By constructing actions on my improved plan I am enabled to dispense with springs which always add much to friction and destroy to a perceivable degree the delicacy of touch and are besides liable to derangement.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is 1. The combination of the escapement jack and check coperating to sustain the hammer in position to repeat and to prevent piano forte and other actions in combination its rebound substantially in the manner set with the jack and hammer for the purpose forth. herein set forth.

2. The inclined escapement as applied to WILLIAM MUNROE. 5 piano forte and other similar actions sub- Witnesses:

stantially in the manner herein set forth. J. B. CROSBY,

3. The application of the toggle joint to JEREMIAH R. CALLAGHAN. 

